[GH-ISSUE #1372] Sync brightness between main and additional monitor doesn't work, after sleep or restart. #781

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opened 2026-05-05 06:41:50 -06:00 by gitea-mirror · 1 comment

gitea-mirror commented

2026-05-05 06:41:50 -06:00

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Originally created by @lutogin on GitHub (May 9, 2023).
Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/1372

Before opening the issue, have you...?

Searched for existing issues
Looked through the wiki
Updated MonitorControl to the latest version (if applicable)

Describe the bug

Sync brights between main and additional monitor doesn't work, after sleep or restart.
MacBook Pro 2015 macOS 11.7.3 (20G1116) + Dell U2722D
and
MacBook Pro 2019 latest macOS + Dell U2722D

Steps to reproduce

Just try to use app. It doesn't work at all. Total glitches!

Brightness does what even it wants, random.
Just install your app. And reboot mac.

Expected behavior

Sync brightness work from the main screen. If in room light - brightness increase, if it is darker - brightness decrease. It's very simple.

Anything else?

No response

Environment Information (please complete the following information)

- macOS version: 11.7.3 (20G1116)
- Mac model: MacBook Pro (Retina, 15-inch, Late 2014)
- MonitorControl version: 4.1.0
- Monitor(s): Dell u2722d
- Apple Silicon/M1 (yes or no): no

Originally created by @lutogin on GitHub (May 9, 2023). Original GitHub issue: https://github.com/MonitorControl/MonitorControl/issues/1372 ### Before opening the issue, have you...? - [X] Searched for existing issues - [X] Looked through [the wiki](https://github.com/MonitorControl/MonitorControl/wiki) - [X] Updated MonitorControl to the latest version (if applicable) ### Describe the bug Sync brights between main and additional monitor doesn't work, after sleep or restart. MacBook Pro 2015 macOS 11.7.3 (20G1116) + Dell U2722D and MacBook Pro 2019 latest macOS + Dell U2722D ### Steps to reproduce Just try to use app. It doesn't work at all. Total glitches! Brightness does what even it wants, random. Just install your app. And reboot mac. ![image](https://github.com/MonitorControl/MonitorControl/assets/20394919/9315b443-46db-4997-9249-00be4a967864) ![image](https://github.com/MonitorControl/MonitorControl/assets/20394919/7fe29107-068d-403e-a5b0-2f34bf73968d) ### Expected behavior Sync brightness work from the main screen. If in room light - brightness increase, if it is darker - brightness decrease. It's very simple. ### Anything else? _No response_ ### Environment Information (please complete the following information) ```markdown - macOS version: 11.7.3 (20G1116) - Mac model: MacBook Pro (Retina, 15-inch, Late 2014) - MonitorControl version: 4.1.0 - Monitor(s): Dell u2722d - Apple Silicon/M1 (yes or no): no ```

gitea-mirror closed this issue

2026-05-05 06:41:52 -06:00

gitea-mirror commented

2026-05-05 06:41:55 -06:00

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Owner

@waydabber commented on GitHub (May 31, 2023):

If you sync brightness from your built-in screen to the external screen and the ambient light sensor (automatic brightness) is enabled, the external display's brightness will change according to the built-in screen. If you use the keyboard to alter the brightness of the external display, the app is trying to keep the delta but if it reaches the min/max end of the range, it can't do that anymore. For a more direct control or if you don't like/understand how syncing works in the app, it's just better to turn it off and change brightness manually as you prefer.

@waydabber commented on GitHub (May 31, 2023): If you sync brightness from your built-in screen to the external screen and the ambient light sensor (automatic brightness) is enabled, the external display's brightness will change according to the built-in screen. If you use the keyboard to alter the brightness of the external display, the app is trying to keep the delta but if it reaches the min/max end of the range, it can't do that anymore. For a more direct control or if you don't like/understand how syncing works in the app, it's just better to turn it off and change brightness manually as you prefer.